That mysterious “M” line on a traditional wedding RSVP card is actually an old etiquette convention. The letter M is meant to begin your title—such as Mr., Mrs., Miss, or Ms. You simply add the rest of your title and name on the line beside it.For example, someone named John Smith might write “Mr. John Smith,” while Jane Smith might write “Ms. Jane Smith.” A married couple could write something like “Mr. and Mrs. John Smith,” depending on how formal or traditional they want to be. The line is essentially the place where guests identify exactly who is accepting or declining the invitation.

The tradition comes from a time when formal wedding invitations followed very strict etiquette rules. Titles were considered important, so instead of simply printing “Name: ______,” stationery designers provided the first letter of the expected honorific. That little M has survived on many modern invitations even though plenty of people no longer recognize what it means.

After writing your name, you would normally check or fill in the section indicating whether you’ll attend. Some cards also ask for the number of guests, meal choice, or other information.

So despite all the confusion, the M doesn’t stand for “maybe,” “married,” or “meal.” It’s simply the beginning of Mr., Mrs., Miss, or Ms.

It’s one of those tiny pieces of old-fashioned wedding etiquette that has managed to stick around long after most people stopped being taught what it means.